Bone implant

ABSTRACT

A system and method for forming a hip implant offering minimal invasiveness is described. The system comprises means for positioning the implant under optical and X-ray control, an implant and an applicator for screwing and expanding the implant. The implant includes an insert body and an expansion tube with cut-outs and slits defining legs. The legs expand radially through windows in the insert body when the expansion tube is pushed against the sloped distal portion of the insert body. The expansion process may be ensured by using an anti-rotation device to prevent the insertion tube from rotating within the insert body. Applicator and implant are provided with means preventing cold welding during the implantation process.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation in part application of U.S.patent application Ser. No. 14/429,783, filed Mar. 20, 2015, which isthe national stage application of PCT/IB2013/002066, filed Sep. 20,2013, which claims the benefit of prior filed U.S. Provisional PatentApplication, Ser. No. 61/703,327 filed 20 Sep. 2012, which priorapplication is incorporated herein by reference.

COPYRIGHT & LEGAL NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The Applicant has no objectionto the facsimile reproduction by anyone of the patent document or thepatent disclosure as it appears in the Patent and Trademark Officepatent file or records, but otherwise reserves all copyright rightswhatsoever. Further, no references to third party patents or articlesmade herein is to be construed as an admission that the presentinvention is not entitled to antedate such material by virtue of priorinvention.

FIELD OF THE INVENTION

This invention relates to a system, devices and methods for bonereinforcement, especially for the treatment of osteoporosis.

BACKGROUND OF THE INVENTION

Osteoporosis, the reduction of bone density, is one of the major reasonsfor femoral neck fractures, affecting millions of elderly peopleworldwide each year. It is, however, increasingly becoming a problemalso for young female athletes (see, e.g., Female Athlete Triad,Switzerland. Magazine for “Sportmedizin und Sporttraumatologie” 48 (3),119-132 (2000), the content of which is incorporated herein byreference). For the treatment of osteoporosis according to theinvention, it is essential that the presence of osteoporosis canreliably be diagnosed. There are indeed a number of ways for thediagnosis of osteoporosis and the prediction of bone fracture. The mostwidely used is dual energy X-ray absorptiometry (DXA). DXA scans areprimarily used to measure the areal bone mineral density. An even morereliable method, yielding directly the volume density of a bone, iscomputed quantitative computer tomography (see for examplehttp://en.wikipedia.org/wiki/Dual-energy X-ray absorptiometry. theentire content of which is hereby incorporated by reference)(See FIGS.11, 12A, 12B and 13). These figures are referred to as a matter ofbackground information and show, in FIG. 12, a DXA scanner adapted toscan the body to evaluate bone mineral density using dual-energy X-rayabsorptiometry. FIGS. 12A and 12B are schematic views of a DEXAassessment of bone mineral density of the femoral neck and of the lumbarspine, respectively. FIG. 13 is the output of a full body scan is shownon a screen of a DEXA scanner.

One way to prophylactically treat osteoporosis is through the use ofpharmaceuticals, which, besides being of limited effectiveness, areoften hampered by serious side effects. A better solution seems,therefore, to be the use of prophylactic implants, enhancing themechanical stability of the bone, thus providing a local and not asystemic way to address the problem. Such implants are generallyintroduced in either of a number of ways, such as (1) through a bore inthe greater trochanter along the femoral neck axis (see for example U.S.Pat. No. 6,679,890 to Margulies and U.S. Pat. No. 6,319,255 to Grundei,the contents of which are hereby incorporated by reference); (2) throughthe intramedullary canal of the proximal femur (see for example U.S.Pat. No. 8,012,155 to Prygoski, the content of which is herebyincorporated by reference); (3) through a bore in Ward's triangle (seefor example US 2009/0112210 to Philippon, the content of which is herebyincorporated by reference).

It is a general feature of the prior art that the bore has been madefrom the side, i.e. in a plane containing the femur body, the femoralneck and the femoral head. This, however, may damage the surroundingsoft tissue.

What is needed is a reliable, simple method of reinforcing osteoporoticbone. What is needed is a method that is devoid of any of the systemicside effects of drugs, while being minimally invasive to avoid softtissue damage.

SUMMARY OF THE INVENTION

A system, device and method is provided for the treatment ofosteoporotic bones, especially of the femoral neck. The system includesa device for positioning the implant under optical and X-ray control, animplant and an applicator for screwing and expanding the implant. Theimplant includes an insert body and an expansion tube with cut-outs andslits defining legs. The legs expand radially through windows in theinsert body when the expansion tube is pushed against the sloped distalportion of the insert body. The expansion process may be better ensuredby an anti-rotation device, which prevents the expansion tube fromrotating within the insert body. The applicator and implant are providedwith means preventing cold welding during the implantation process.

It is another object of the invention to provide a means for minimalinvasiveness during the introduction of a hip implant.

It is another object of the invention to provide an expandable structurewithin bone, which is able to guide healthy cortical bone to lessfunctional trabecular bone areas, thereby enhancing its stability.

It is another object of the invention to provide accurate and simplepositioning of a hip implant.

It is another object of the invention to provide a hip implant and anapplicator for its positioning, insertion and expansion.

It is another object of the invention to provide a method for thecreation of a hip implant under optimal visual and X-ray control.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic view of the positioning of a hip implant in theregion of Ward's triangle.

FIG. 1B is a schematic view of an alternative positioning of a hipimplant into the region of Ward's triangle.

FIG. 2A is a side view of an unassembled hip implant.

FIG. 2B is a perspective view of an unassembled hip implant. FIG. 2C isa perspective view of an assembled hip implant before expansion. FIG. 2Dis a perspective view of an assembled hip implant after expansion. FIG.3A is a perspective view of an applicator for inserting a hip implant.

FIG. 3B is a detailed perspective view of components of the applicator.

FIG. 3C is a detailed perspective view of a hip implant mounted on anassembled applicator.

FIG. 4 is a perspective view of the applicator with a mounted implantand integrated positioning control.

FIG. 5A is a side view of another embodiment of a hip implant inunassembled form. FIG. 5B is a side view of the embodiment of FIG. 5A,in an assembled form.

FIG. 6A is a perspective view of the embodiment of FIG. 5A inunassembled form. FIG. 6B is a perspective view of the embodiment ofFIG. 5A mounted on the applicator. FIG. 6C is a side view of theembodiment of FIG. 5A mounted on the applicator.

FIG. 7A is a side view of a device for controlling the position of hipimplants, before implant hole drilling and implant positioning.

FIG. 7B is a side view of the device of FIG. 7A for controlling theposition of hip implants, after implant hole drilling and duringpositioning.

FIG. 8 is a method for inserting and forming a hip implant.

FIG. 9 is . . . a method of the invention for treating osteoporosis.

FIG. 10A is a schematic, exploded view showing more detail of thealternative placement strategy illustrated in FIG. 1B.

FIG. 10B is a schematic, assembled view showing more detail of thealternative placement strategy illustrated in FIG. 1B.

FIG. 11 is a device used for measuring bone density using dual-energyX-ray absorptiometry.

FIGS. 12A and 12B are schematic views of a DEXA assessment of bonemineral density of the femoral neck and of the lumbar spine,respectively.

FIG. 13 is a schematic view of a full body scan appearing on a screen ofa DEXA scanner.

Those skilled in the art will appreciate that elements in the Figuresare illustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, dimensions may be exaggerated relative toother elements to help improve understanding of the invention and itsembodiments. Furthermore, when the terms ‘first’, ‘second’, and the likeare used herein, their use is intended to distinguish between similarelements and not necessarily for describing a sequential orchronological order. Moreover, relative terms like ‘front’, ‘back’,‘top’ and ‘bottom’, and the like in the Description and/or in the claimsare not necessarily used for describing exclusive relative position.Those skilled in the art will therefore understand that such terms maybe interchangeable with other terms, and that the embodiments describedherein are capable of operating in other orientations than thoseexplicitly illustrated or otherwise described.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following description is not intended to limit the scope of theinvention in any way as they are exemplary in nature, serving todescribe the best mode of the invention known to the inventors as of thefiling date hereof. Consequently, changes may be made in the arrangementand/or function of any of the elements described in the exemplaryembodiments disclosed herein without departing from the spirit and scopeof the invention.

In the following, a complete system of hip implants and its use will bedescribed. The system comprises the implant itself, and additionaldevices or “applicators” used for precise positioning of the implant.

Referring now to FIG. 1A, part of a femur 100 is shown, with femur body102, greater trochanter 104, femur head 106 and femur neck 108. The bore110 for a hip implant is drilled through the cortical bone over Ward'striangle region of the femur neck, in a direction perpendicular to theplane containing femur body 102, femur neck 108 and femur head 106.According to the invention, this positioning of the bore has proven tobe minimally invasive, as it minimizes soft tissue damage while placingthe implant. The size of bore 110 is in the range of 4 to 8 mm,preferably about 5 mm. Circle 120 indicates the maximal reach in termsof lateral expansion of the implant. The diameter of the circle 120 is,for example, in the range of 4.6 cm, and it may be obtained using animplant having 1.9 cm long legs (see for example FIGS. 2 and 5). Inanother embodiment (not shown) having longer legs, regions of thefemoral head 106 or the greater trochanter 104 may be reached.

As an alternative placement strategy illustrated in FIG. 1B, the hipimplant 200 of the present invention may be inserted into the region ofthe femoral neck 108 from the greater trochanter region 104 of the femur100. In accomplishing this placement strategy, a bore 110′ is made fromthe greater trochanter 104 toward the femoral head 106 axially to thefemoral neck 108 and perpendicular to a plane 120′ of the cross-sectionof the neck 108. Using this positioning strategy, the regions of thefemoral head 106 and the greater trochanter 104 may also be reached byadjusting the depth of the bore 120′.

Referring now to FIGS. 2A-2B, the unassembled components of a hipimplant 200 are shown, along with an implant in its assembled state (seeFIG. 2C) and finally in expanded form (see FIG. 2D). Referring inparticular to FIGS. 2A-2B, the main components are made up of two parts,a guiding insert body 210 which is screwed into the bore 110, and anexpansion tube 230 with slits 232 and cut-outs 233, which, whendeformed, form at least two and preferably four or more legs 234. FIG.2A shows an optional cap 240 for sealing the implant at its proximalend. The insert body 210 is made up of a proximal portion 217 and adistal portion 216 connected at the distal end 211 of the proximalportion 217 by arms 213 to a proximal end 218 of the distal portion 215.The proximal portion 217 of the insert body 210 has two screw threads,the first thread 212 for screwing the implant into bore 110, and thesecond thread 222, of only a few turns located at a proximal end 215 ofthe proximal portion 217, for fixing the implant to the applicator 300,400 used for mounting the implant (see also FIGS. 3A-3C and 4). The arms213, extending between the proximal portion 217 of the insert body 210and the distal portion 216, define windows 214. The proximal surface 218of the distal portion 216 of the insert body 210 is preferably sloped.The angle of the sloped surface 218 is preferably about 45 degrees withrespect to the axis of insert body 210.

During assembly of the implant 200, 500, the expansion tube 230 may beslid into hollow insert body 210 until legs 234 make contact with thesloped surface 218 of distal portion 216, the deflection plate, as shownin FIG. 2C. Upon pushing expansion tube 230 further into insert body210, the legs 234 are deflected outside of windows 214 by beingoutwardly directed against the sloped surface 218. This processinitiates the lateral expansion of the legs 234 of the implant 200, 500,which is shown in FIG. 2D in its final form. The extent to which legs234 extend laterally depends on a number of parameters, such as thematerial, for example stainless steel or titanium, and thickness ofexpansion tube 230, and the sloped surface 218 of the distal portion216, as well as the angle of the slope.

The insert body 210 may contain a flange 224 between screw threads 212and 222. As shown in FIG. 2B, flange 224 optionally has two flat regions226 on opposite sides of insert body 210. According to the invention,the flat regions 226 are provided to take up the torque applied by theapplicator to insert body 210 while the insert body is screwed into bore110 (see also FIG. 3). This feature minimizes the risk of cold weldingof the applicator 300, 400 to the insert body 210 during screwing of theimplant 200, 500 into bore 110.

Referring now to FIG. 3, a first embodiment 300 of an applicator 300 forscrewing the implant 200 into bore 110 may comprise a tube 340 intowhich guiding insert body 210, 310 can be screwed. In order to avoid thetorque being applied to screw thread 222 during screwing the sleeve intothe cortical bone, which may run the risk of cold welding the threads, asecond tube 350, the inner diameter of which exceeds the outer diameterof tube 340, is slid onto tube 340. The end facing the implant of tube350 may contain extensions 352 on opposite sides, as shown in FIGS.3A-3B. These extensions interface with the flat regions 326 of insertbody 210, 310, as shown in FIG. 3C. The torque exerted during screwingthe guiding sleeve into the cortical bone may hence be applied to theflat regions 326, whereby the risk of cold welding of any parts isminimized. Torque may be applied by means of lever 356 which may beinserted into holes 354 in tube 350. Larger holes in inner tubes 340,360 help ensure that the torque exerted by lever 356 is exertedprimarily on the outer tube 350. Torque is also applied on tube 340, butonly to a small extent. It is important to note that the torque is nottransmitted primarily to the screw thread but instead to the flats 226.

Once the insert body 210 has been properly screwed into the bore and thelever 356 removed, an innermost tube 360 may serve to push expansiontube 230 towards the sloped surface 218 of the distal portion 216, 316,thereby expanding legs 234, 334 into the inner space of the femur neck108.

Referring now to FIG. 4, another embodiment 400 of an applicatorprovides a more accurate positioning of the implant 200, 500 underoptical and X-ray control. Here, the outermost tube 350, 450 exertingthe torque on insert body 310, 410 during the torquing of screw thread312, 412 into the cortical bone may contain guiding grooves 458. Theseguiding grooves keep slider 470 from rotating around the axis of theapplicator as it slides along tube 350, 450. Slider 470 may containoptical marks 472 facing the surgeon during the operation, allowing himto position legs 234, 334 accurately with respect to the axis of femoralneck 108. Additional positioning control may be accomplished byproviding X-ray absorbing material 474 aligned with optical marks 472 ofslider 470. This permits direct observation by X-rays in addition to thevisual method of positioning the implant. Applicator 400 may furthermorebe equipped with lever 482 by means of which the innermost tube 460 canbe pushed against expansion tube 230 in order to expand legs 234, 334 ofexpansion tube 230. Removable cap 462 screwed onto the innermost tube460 may prevent pushing of expansion tube 230 by any accidental movementof lever 482.

Referring now to FIG. 5, another embodiment 500 of insert body 510 maycontain a section 525 above screw thread 212, 312, 512 which may beshorter than the corresponding section of insert body 210, 310.Accordingly, the screw thread 522 used for attaching insert body 510 toapplicator 400 may be located on the inside of section 525, as shown inFIGS. SA-SB. This has the advantage of causing even less soft tissuedamage during implantation, because of a less protruding outermost tubeof applicator 400 (see also FIG. 6). This design also allows a moreshallow structure outside of the femoral neck, which advantageouslyreduces irritation of soft tissue.

Referring now to FIG. 6A-6C, this embodiment of the insert body 510, 610optionally incorporates an anti-rotation device 627, which in oneembodiment is essentially a specially shaped frame of window 214, 614,as shown in FIGS. 6B-6C. This shape prevents expansion tube 230, 530,630 from rotating while it is pushed into the insert body and during thepositioning of the implant in the bone. As a result, legs 234, 534, 634are free to expand through window 214, 614, while expansion tube 230,530, 630 is pushed against the inclined or sloping surface 218, 518, 618of distal portion 216, 516, 616. The flats 626 of section 525 are formedto absorb the torque exerted by the extensions 652 of applicator 400while the insert body 510,610 is screwed into the bore 110.

In other embodiments insert body 210, 310, 410, 510, 610 of the implant200, 500 may be fastened in different ways to applicator 300, 400 ratherthan by screw thread 222, 522. The fastening mechanism may, for example,comprise a bayonet lock, a clamping fastener, or any other means bywhich the applicator is detachable from the insert body of the implantafter the latter has been screwed into bore 110 and expanded.

Referring now to FIG. 7, the system for forming a hip implant maycomprise an additional device 700 for precise implant positioning.Device 700 may comprise a guiding tube 790 which may be placed on thecortical bone 792 at the chosen location of bore 110, 793, as shown inFIG. 7A. Guiding tube 790 is provided with optical markers with respectto which optical markers 472, 772 on slider 470, 770 of the applicatorare aligned in order to allow precise positioning of the implant, asshown in FIG. 7B. Guiding tube 790 may furthermore be equipped withmarkers 796, made from X-ray absorbing material, aligned with theoptical marks 794. During the operation, markers 796 may be alignedunder X-ray control with X-ray markers 474, 774 on slider 470, 770 ofthe applicator, allowing for even better control of the process ofimplant formation and positioning. In addition, alignment of opticalmarkers 794 with the guiding grooves 458 or other optical lines, marks,etc. on tube 350, 450, 650 without the use of the slider 470, may aid inpositioning the implant.

Referring now to FIG. 8, a method 800 for the use of the system forforming a hip implant includes any one of a list of steps: in anoptional first step 810, performing diagnostic tests for osteoporosis;in a second step 812, choosing the location of the implant; in a thirdstep 814, placing a guiding tube 790 for positioning control; in afourth step 816; forming the bore under precise positioning control; ina fifth step 818, inserting the implant by means of an applicatorthrough the guiding tube; in a sixth step 820, screwing the implant intothe bone; in a seventh step 822, expanding the implant; in an eight step824, optionally filling the implant and adjacent cancellous bone regionsby a filler material (including calcium phosphate, bone cement or thelike) preferably through the applicator; in a ninth step 826, removingthe applicator; and, in a tenth step 830, optionally inserting a cap forsealing the implant.

The assembled hip implant 200, 500 has an aperture or bore 231, 631,631′ passing through its central axis. When the hip implant 200, 500device is installed, this central bore 231, 631, 631′, it can allowaccess to the cancellous region of the bone. Utilizing the aperture orbore 231, 631, 631′, other prosthetics or instruments (e.g., a trocar)and/or biological agents (e.g., a bone growth biologic) can be insertedinto the implant site.

Referring now to FIG. 9, in another embodiment, a method of treatingosteoporosis is provided which directs healthy cortical bone to lessfunctional trabecular bone areas, thereby substituting the lessfunctional trabecular areas of the bone with healthy bone mass, themethod including several steps. In a first step 910, the insert isinserted into a bone. In a second step 920, the insert is expandedinside the bone. In a third step 930, a bone growth promoter isoptionally inserted through the insert into the bone. In a fourth step940, the osteoconductive properties of the insert are used to attractand guide bone growth. The osteoconductive properties of said insert maybe enhanced by surface treatment or coating of the insert with bonegrowth enhancing substances or structures. Additionally, the insertionand making of the implant provides a bridging from cortical totrabecular bone areas in a flexible way. Mechanical force from thecortical bone areas may be transduced to the implant body and legs,thereby stimulating bone growth by the intrinsic property of bone torebuild and restructure at sites of mechanical loading. By designing andmaking of said implant in a semi-rigid, rather than rigid way, stressshielding with all negative consequences on the stability of the bone isavoided. The rationale behind this is, that the quality of bone candeteriorate in the vicinity of implants due to stress shielding. Becausebone is a dynamic tissue, it reacts on loading by building up tissue andgets weaker, when not loaded. By repeatedly transducing the force fromcortical areas (via the insert and legs) to trabecular areas, theseareas may react by bone growth stimulation/or the ingrowth from corticalareas may be of better quantity and quality.

Referring now to FIGS. 10A and 10B, which show more detail of thealternative placement strategy illustrated in FIG. 1B, the hip implant200′ of the present invention having a body 510′ elongated to a length X(to suit the patient's particular bone size) when compared to the otherembodiments presented herein, may be inserted such that the legs 234′may be extended into the region of the femoral neck 108 by insertion ofthe implant 200′ from the greater trochanter region 104 of the femur100. Threads 512′ may extend along the entire body 510′ of the implant200′. However, only a few threads 512′ are required to be able to drivethe insert 200′ into the desired location. Windows (not shown) areoptionally added along the body 510′ to allow leaching out of bonegrowth promoting substances which may be placed therein. Inaccomplishing this placement strategy, a bore 110′ is made from thegreater trochanter 104 toward the femoral head 106 axially to thefemoral neck 108 and perpendicular to a plane 120′ of the cross-sectionof the neck 108. The insert body 510′ is inserted in the bore 110′ andthe tool described in FIG. 3A-3C drives the insert body to the desiredposition, where the windows 214′ are adjacent the femoral neck area 108.The expansion tube 230 is then inserted, followed by a spacer 235. Thespacer 235 may be made such that it is porous to contain bone growthpromoting compounds. The spacer 235 may also be a power metal pressedpart, pressed together with bone growth promoting agents. This spacer235 allows use of a standard length expansion tube 230 and permits theextrusion of the expansion tube 230 through the windows 214′, such thatthe legs 234′ extend through the windows 214′, breaking up thetrabecular bone and allowing bone regrowth and reinforcement of thefemoral neck 108. A cap 240′ may be installed over the end of the insert230, to protect against damage to adjacent soft tissue.

It should be appreciated that the particular implementations shown andherein described are representative of the invention and its best modeand are not intended to limit the scope of the present invention in anyway. For instance, tapping in of the innermost tube 360, 460 into theguiding insert body 210, 510 with a rod- or trocar-like instrument (notshown) and a mallet (not shown) is an alternative method for expandingthe implant 200,500. Of course, there are any number of different waysto press the expansion tube 230, 530 into the guiding insert body 210,510 such as by turning a thread which drives the expansion tube therein.In addition, the shape of the surface 218, 518 of the deflection plate216, 516 may comprise any shape suitable for deflecting and evendirecting the deflection of the legs 234, 534. For example, theselection of an appropriate shape for the legs 234, 534 and thedeflection plate 216, 516 may be made to cause the legs to spiralthrough the cancellous bone, in order to create a larger cavity.

Moreover, the system contemplates the use, sale and/or distribution ofany goods, services or information having similar functionalitydescribed herein.

The specification and figures should be considered in an illustrativemanner, rather than a restrictive one, and all modifications describedherein are intended to be included within the scope of the inventionclaimed. Accordingly, the scope of the invention should be determined bythe appended claims (as they currently exist or as later amended oradded, and their legal equivalents) rather than by merely the examplesdescribed above. Steps recited in any method or process claims, unlessotherwise expressly stated, may be executed in any order and are notlimited to the specific order presented in any claim. Further, theelements and/or components recited in apparatus claims may be assembledor otherwise functionally configured in a variety of permutations toproduce substantially the same result as the present invention.Consequently, the invention should not be interpreted as being limitedto the specific configuration recited in the claims.

Benefits, other advantages and solutions mentioned herein are not to beconstrued as critical, required or essential features or components ofany or all the claims.

As used herein, the terms “comprises”, “comprising”, or variationsthereof, are intended to refer to a non-exclusive listing of elements,such that any apparatus, process, method, article, or composition of theinvention that comprises a list of elements that includes not only thoseelements recited, but may also include other elements described in theinstant specification. Unless otherwise explicitly stated, the use ofthe term “consisting” or “consisting of” or “consisting essentially of”is not intended to limit the scope of the invention to the enumeratedelements named thereafter, unless otherwise indicated. Othercombinations and/or modifications of the above-described elements,materials or structures used in the practice of the present inventionmay be varied or adapted by the skilled artisan to other designs withoutdeparting from the general principles of the invention.

The patents and articles mentioned above are hereby incorporated byreference herein, unless otherwise noted, to the extent that the sameare not inconsistent with this disclosure.

Other characteristics and modes of execution of the invention aredescribed in the appended claims.

Further, the invention should be considered as comprising all possiblecombinations of every feature described in the instant specification,appended claims, and/or drawing figures, which may be considered new,inventive and industrially applicable.

Copyright may be owned by the Applicant(s) or their assignee and, withrespect to express Licensees to third parties of the rights defined inone or more claims herein, no implied license is granted herein to usethe invention as defined in the remaining claims. Further, vis-a-vis thepublic or third parties, no express or implied license is granted toprepare derivative works based on this patent specification, inclusiveof the appendix hereto and any computer program comprised therein.

Additional features and functionality of the invention are described inthe claims appended hereto. Such claims are hereby incorporated in theirentirety by reference thereto in this specification and should beconsidered as part of the application as filed.

Multiple variations and modifications are possible in the embodiments ofthe invention described here. Although certain illustrative embodimentsof the invention have been shown and described here, a wide range ofchanges, modifications, and substitutions is contemplated in theforegoing disclosure. While the above description contains many specificdetails, these should not be construed as limitations on the scope ofthe invention, but rather exemplify one or another preferred embodimentthereof. In some instances, some features of the present invention maybe employed without a corresponding use of the other features.Accordingly, it is appropriate that the foregoing description beconstrued broadly and understood as being illustrative only, the spiritand scope of the invention being limited only by the claims thatultimately issue in this application.

What is claimed is:
 1. A system for implanting a bone implant, thesystem including the bone implant and an applicator, the bone implantcomprising: a) an insert body having a proximal end, a mid-point, and adistal end, the insert body further having an externally threadedproximal portion adjacent the proximal end of the insert body, theproximal portion configured to affix the insert body to cortical boneand a distal portion separated from the proximal portion by at least twoarms defining windows therebetween, and b) an expansion tube fittinginto said insert body, wherein cut-outs define at least two legs; theapplicator being configured to be attached to the insert body foraffixing the insert body into the bone prior to pressing the expansiontube into the insert body, the pressing splaying the at least two legsin a distal direction so as to agitate cancellous bone.
 2. The system ofclaim 1 further comprising a positioning device configured to guide saidapplicator into a bore in the bone.
 3. The system of claim 1, whereinsaid distal portion has a slope configured to deflect said legs radiallyoutwards through said windows when said expansion tube is pushed againstsaid slope.
 4. The system of claim 1, wherein said insert body comprisesan anti-rotation device which prevents said expansion tube from rotatingwhen forcing said legs to be expanded through said window when saidexpansion tube is pushed against said slope.
 5. The system of claim 1,wherein said insert body is configured to be attached to said applicatorby a device selected from one of a group of devices consisting of ascrew thread, a bayonet lock and a clamping fastener.
 6. The system ofclaim 1 comprising a feature which avoids cold welding of saidapplicator to said insert body during screwing said sleeve into the saidbore.
 7. The system of claim 1, wherein said applicator and said insertbody include a device for relative position control, including opticalmarks and X-ray marks.
 8. The system of claim 1, wherein the applicatoris configured to insert the insert body and expansion tube of theimplant into a guiding tube, to screw said implant into the bone, and toexpand said implant.
 9. The system of claim 1, wherein the insert bodyis dimensioned so that, upon insertion in a region of the Ward'striangle on the femoral neck, the proximal portion of the insert bodyaffixes to the cortical bone on one side of the femoral neck and thedistal portion extends to the cancellous bone region of the femoralneck.
 10. The system of claim 1, wherein the at least two legs of theexpansion tube have at least one slit or scoring, which facilitatessplitting of a leg into two partial legs as the expansion tube ispressed into the insert body, thereby splaying the legs out distally.11. The system of claim 1, wherein the at least two legs splay out inresponse to deflection by a deflection surface on the insert body. 12.The system of claim 1 wherein the insert body further includes a flangethat is configured to interface with the applicator.
 13. A bone implantcomprising: (a) an insert body having a proximal end, a mid-point, and adistal end, the insert body further having an externally threadedproximal portion adjacent the proximal end of the insert body, theproximal portion configured to affix to cortical bone and a distalportion separated from the proximal portion by at least two armsdefining windows therebetween, the insert body further including aflange at the proximal end configured to interface with an applicator;and (b) an expansion tube fitting into said insert body, wherein atleast two slits define at least two distally directed legs.
 14. The boneimplant of claim 13, wherein an aperture passes therethrough, to allowaccess, when implanted, to a cancellous region of a bone.
 15. The boneimplant of claim 13, wherein an aperture passes therethrough, to allow abiological agent to be inserted into the implant site.